GFS2: Adding missing unlock_page()

gfs2_write_begin() calls grab_cache_page_write_begin() that returns *locked*
page. Correspondent error-handling path lacks for unlock_page() call:

> out:
> 	if (error == 0)
> 		return 0;
>
> 	page_cache_release(page);

The whole system hangs if gfs2_unstuff_dinode() called from gfs2_write_begin()
failed for some reason.

Reported-by: Maxim <maxim.patlasov@gmail.com>
Signed-off-by: Maxim <maxim.patlasov@gmail.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/fs/gfs2/aops.c b/fs/gfs2/aops.c
index 4f36f8832b9b..aad77e4f61b5 100644
--- a/fs/gfs2/aops.c
+++ b/fs/gfs2/aops.c
@@ -695,6 +695,7 @@ out:
         if (error == 0)
                 return 0;
 
+        unlock_page(page);
         page_cache_release(page);
 
         gfs2_trans_end(sdp);